This invention relates generally to a cement plant and more particularly to tuning a raw mix proportioning controller in a cement plant.
A typical cement plant uses raw material such as limestone, sandstone and sweetener to make cement. Transport belts (e.g. weighfeeders) transport each of the three raw materials to a mixer which mixes the materials together. A raw mill receives the mixed material and grinds and blends it into a powder, known as a xe2x80x9craw mixxe2x80x9d. The raw mill feeds the raw mix to a kiln where it undergoes a calcination process. In order to produce a quality cement, it is necessary that the raw mix produced by the raw mill have physical properties with certain desirable values. Some of the physical properties which characterize the raw mix are a Lime Saturation Factor (LSF), a Alumina Modulus (ALM) and a Silica Modulus (SIM). These properties are all known functions of the fractions of four metallic oxides (i.e., calcium, iron, aluminum, and silicon) present in each of the raw materials. Typically, the LSF, ALM and SIM values for the raw mix coming out of the raw mill should be close to specified set points.
One way of regulating the LSF, ALM and SIN values for the raw mix coming out of the raw mill to the specified set points is by providing closed-loop control with a proportional controller. Typically, the proportional controller uses the deviation from the set points at the raw mill as an input and generates new targeted set points as an output for the next time step. Essentially, the closed-loop proportional controller is a conventional feedback controller that uses tracking error as an input and generates a control action to compensate for the error. One problem with using the closed-loop proportional controller to regulate the LSF, ALM and SIM values for the raw mix. coming out of the raw mill is that there is too much fluctuation from the targeted set points. Too much fluctuation causes the raw mix to have an improper mix of the raw materials which results in a poorer quality cement. In order to prevent a fluctuation of LSF, ALM and SIM values for the raw mix coming out of the raw mill, there is a need for a system and a method that can ensure that there is a correct mix and composition of raw materials for making the cement.
This invention relates to a system, method and a computer readable medium that stores computer instructions for tuning a raw mix proportioning controller. In this embodiment, there is a plurality of target set points. A cement plant simulator simulates the operation of a cement plant according to a plurality of set points. A fuzzy logic supervisory controller controls the operation of the cement plant simulator in accordance with the plurality of target set points. More specifically, the fuzzy logic supervisory controller tracks error and change in tracking error between the plurality of set points of the cement plant simulator and the plurality of target set points and provides a control action to the cement plant simulator to minimize the tracking error. A tuner, coupled to the cement plant simulator and the fuzzy logic supervisory controller, optimizes the tracking between the cement plant simulator and the plurality of target set points.